Which statement regarding navicular fractures is NOT true?

The statement that navicular fractures usually show up on an x-ray immediately after injury is not true. This is primarily because navicular fractures, especially those in the scaphoid bone (often referred to as the navicular bone in the wrist), can be subtle and may not be visible on initial x-rays. Due to the bone's unique anatomy and the overlapping of structures in the wrist, these fractures can be easily missed right after the injury occurs.

Follow-up imaging, typically in 1-2 weeks, is often necessary to reveal signs of fracture that might not be apparent at the time of the incident. This delayed appearance on x-rays is a critical aspect of managing such injuries, as overlooking a fracture can lead to complications such as nonunion.

The other statements reflect accurate information about navicular fractures. They often do require surgical intervention due to the high risk of poor healing associated with the nature of the blood supply to the scaphoid. A higher rate of nonunion is indeed noted in these fractures when compared to others in the wrist, emphasizing the importance of careful assessment and management.